Printing Solar Cells with Inkjet Printers

The idea of harnessing usable, clean, free energy from the sun is no new idea.  The methods involved with the production of traditional photovoltaic (also known as PV) cells are exactly that…traditional.  Recently, innovations in the manufacturing process of these energy harnessing components has led to a breakthrough that may change the way all of us think about the possibilities of harnessing solar energy.

What exactly is “photovoltaics?” defines “photovoltaics” as a field of semiconductor technology involving the direct conversion of electromagnetic radiation as sunlight, into electricity.  The important words in this definition are: technology, conversion, sunlight, and electricity.

In the traditional approach to produce a technological device that converts sunlight into electricity, an amount of very pure semiconductor-grade polysilicon is used. Polysilicon is melted into an ingot, or block, of silicon either by growing a pure crystalline silicon ingot from a seed crystal taken from the molten polysilicon, or by casting the molten polysilicon into a block. Individual “wafers” are then sliced from the ingots using wire saws and then placed under a surface etching process. Once the wafers are cleaned, they are placed in a “phosphorus diffusion furnace”, creating a thin semiconductor layer around the entire outer surface of the cell. Finally, the finishing touches that allow the component to be used in an electrical system are made.  The result is a rigid and very fragile component that is able to create electricity from sunlight. 

However,  it is not the only way photo-harnessing materials are made. As is common in any technological field, whenever there is a demand, there will be innovation.

Imagine being able to push print on your home printer and out pops a solar cell!  While the consumer market may not be in the reality of this visualization quite yet, creative minds at Massachusetts based Kanarka Technologies and San Jose based Nanosolar have already been experimenting with the idea of printing solar harnessing material using the inkjet process for the past few years.

The inkjet process is best easily visualized by observing a home-based printer that uses the same process.  An inkjet printer, in the simplest terms, propells droplets of ink onto paper to create a digital image.  The same basic premise is used when producing these new paper-thin solar film layers-propelling droplets of something (in this case, copper-indium-gallium-selenium instead of ink) onto a substrate.  In theory, the result could be giant rolls similarly sized to paper rolls used in schools for arts and crafts being pumped out by industrial printing apparatuses.  What the printing press did for literature, the inkjet printer may be able to do for photovoltaics.

Numerious types of products have already been revealed since the commercial development of thin film solar material.  Products such as solar laptop chargers, solar cell phone chargers, and even roofing material for homes are just some of the examples of products that may have not been possible, or feasible, to create using a typical rigid polysilicon design.  A flexible design, such as the one used in thin film photovoltaic technology, will allow engineers to design products for consumers without being limited to the shape of the object or its placement on a structure due to its weight and necessary structural support.  Thin film PV could essentially be “wrapped” around a rigid surface much like decorative paper is used to wrap a gift. 

With the promise to deliver a product that is more versatile, easier to produce, and more cost-effective, there is a natural skepticism that the product may be of lesser quality.  In the case of thin film photovoltaics there is no exception.  However, while the physical  and commercial quality may be uncompromised due to an individual company’s quality assurance and quality control standards, the quality that comes into question is actually the material’s ability to absorb sunlight, not quality as in how well it is made.  There are many differring statistics representing efficiencies of conventional polysilicon designed solar cells versus the new innovative thin film solar technology, but there is one common factor among them that is unarguable-the efficiencies of the conventional design are all higher. 

Additionally, there is argument that the resources that are used to actually produce the second generation solar products are in fact very limited themselves.  The copper, indium, gallium, selenium needed to produce solar thin film, some say, may become no different of a limited resource than oil if the demand for these products increases.

With the rising cost of well…everything, this breakthrough in PV technology may have arrived just in time.  A new movement of human awareness has been taking place over the past few years  resulting in the development of popularly branded “green” technologies. As is seen with the initiative taken by companies such as the previously mentioned Kanarka Technologies and Nanosolar, the idea of “going green” or being “ecoconscious” isn’t just a trend.  Combine the vast potential for engineering applications, the simplicity of the inkjet printing process,  and the cultural awareness of “green” technologies as a necessary integration to provide clean energy and the result is a product that just may be the future of solar power possibilities for residential and commercial consumers alike.